JP2010130831A - Outer rotor type brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an outer rotor type brushless motor which is reduced in mass and has a smaller lock current. <P>SOLUTION: The outer rotor type brushless motor 1 includes a stator 2 having a stator core 3 and a stator coil 4 mounted on the stator core 3, and a rotor 5 disposed rotatably outside the stator 2. The stator coil 4 includes a plurality of coils that are formed by concentratively winding conductors around teeth 3b, each conductor having a conductive portion made of a metal wire rod with a density ρ1 of 2.5 [g/mm<SP>3</SP>] or more and 3.0 [g/mm<SP>3</SP>] or less, the density ρ1 satisfying the relation 0.2×ρ0≤ρ1≤0.5×ρ0 with the density ρ0 of a magnetic material forming the stator core 3 of the stator 2, and with a specific resistance of 2.5×10<SP>-8</SP>[Ω*m] or more and 3.0×10<SP>-8</SP>[Ω*m] or less, and an insulating portion made of a synthetic resin covering the outer peripheral surface of the conductor portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an outer rotor type brushless motor, and more particularly to a stator coil attached to the stator core.

  The outer rotor type brushless motor includes a stator and a rotor that is rotatably disposed on the outer side in the radial direction of the stator. The stator has a stator core and a stator coil attached to the stator core, and the stator core is formed of a magnetic material, and integrally protrudes radially outward from the outer peripheral surface of the stator core body in a radial direction, And a plurality of teeth formed at equal pitches in the circumferential direction. The stator coil has a plurality of windings wound around each tooth of the stator core by concentrated winding.

  The rotor is formed in a cylindrical shape, and includes a rotor yoke disposed on the outer side of the stator so as to face each of the teeth, and a plurality of magnets mounted on the inner wall of the rotor yoke at equal circumferential pitches so as to face the teeth.

  As described above, the outer rotor type brushless motor has the rotor disposed on the radially outer side of the stator, so the circumferential length of the rotor yoke is longer than that of the inner rotor type in which the rotor is disposed on the radially inner side of the stator. . Therefore, the volume of the magnet attached to the rotor yoke can be increased, and the output performance of the motor can be increased. Further, as described above, the rotor of the outer rotor type brushless motor is rotatably arranged on the outer side in the radial direction of the stator, and the outer diameter of the rotor is larger than that of the inner rotor type. Therefore, the inertia of the rotor is increased, and the torque ripple generated in the rotor is reduced.

  Further, the inner rotor type brushless motor has a structure in which a magnet is attached to the outer wall of the rotor yoke, whereas the outer rotor type brushless motor has a structure in which a magnet is attached to the inner wall of the rotor yoke. Therefore, in the inner rotor type brushless motor, it is necessary to take special measures to prevent the magnet from separating from the rotor yoke due to the rotation of the rotor, but in the outer rotor type brushless motor, it is not necessary to take such measures in particular. Can be manufactured with a simple structure (see, for example, Patent Document 1).

As described above, the outer rotor type brushless motor has many advantages compared to the inner rotor type brushless motor. Therefore, as an application in which the advantage is utilized, for example, a fan motor for cooling an automobile radiator, etc. Used as electrical equipment for automobiles.
JP 2008-259364 A

  Motors mounted on automobiles as electrical components for automobiles are strongly required to reduce the weight of the motor in order to improve the fuel consumption of the automobile, and the need for reducing the weight of the motor is also high for the outer rotor type brushless motor.

  A motor driving driver for supplying a control current for driving the motor to the motor is connected to the motor, and this driver operates together with the motor. This driver is provided with a protective element to prevent the driver itself from being damaged when an excessive current is supplied to the motor.

  When the rotation of the motor is locked by an external load, a high current lock current flows through this protective element. This protective device increases in size in proportion to the current value of the lock current and is expensive. It will be something. Therefore, in order to simplify the protection element, it is required to reduce the current value of the lock current of the motor. Naturally, the reduction of the current value of the lock current is also required in the outer rotor type brushless motor.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an outer rotor type brushless motor with reduced mass and a small lock current.

In order to solve the above problems, an outer rotor type brushless motor according to claim 1 of the present invention is formed of a magnetic material, and has an annular stator core body and a radially outer side from the outer peripheral surface of the stator core body. A stator core having a plurality of teeth protruding integrally in a radial direction and formed at a constant pitch in the circumferential direction, a stator having a stator coil mounted on the stator core, a cylindrical shape, and the teeth outside the stator A rotor yoke disposed opposite to the teeth, and a plurality of magnets mounted on the inner wall of the rotor yoke at equal pitches in the circumferential direction so as to face the teeth, and a rotor disposed rotatably with respect to the stator. In the outer rotor type brushless motor provided, the stator coil has a density ρ1 of 2.5 [g. mm ^3] or 3.0 [g / with mm ^3] or less, relative density .rho.0 of the magnetic material forming the stator core of the stator, the density .rho.1 is 0.2 × ρ0 ≦ ρ1 ≦ 0.5 × a conductor portion formed of a metal wire having a relation of ρ0 and having a specific electric resistance of 2.5 × 10 ⁻⁸ [Ω · m] or more and 3.0 × 10 ⁻⁸ [Ω · m] or less; And a conductive wire having an insulating portion made of synthetic resin coated on the outer peripheral surface of the conductor portion, from the radially outer side of the teeth protruding radially before the rotor is rotatably arranged with respect to the stator. A winding nozzle is inserted into a slit formed between adjacent teeth, and the winding nozzle has a plurality of windings wound around each tooth by concentrated winding.

  Furthermore, in claim 2 of the present invention, the conductor portion of the conducting wire forming the winding is mainly composed of aluminum, and the stator core is composed mainly of iron.

As described above, in the present invention, the density ρ1 of the wire forming the conductor portion of the conductive wire used for the winding of the stator coil is 2.5 [g / mm ³ ] or more and 3.0 [g / mm ³ ] or less. It is. This density ρ1 is about one-third or less of the density of copper widely used as the wire of the conductive wire used for the winding of the stator coil. Further, the density ρ1 of the wire is about half or less than the density ρ0 of the magnetic material used for the stator core.

  Therefore, the mass of the stator coil occupying the stator is small, and the outer rotor type brushless motor of the present invention is reduced in weight as a whole by using a conductive wire having a density ρ1, and the mass is reduced.

Furthermore, the specific electric resistance of the wire forming the conductor portion of the conducting wire used for the winding of the stator coil is 2.5 × 10 ⁻⁸ [Ω · m] or more and 3.0 × 10 ⁻⁸ [Ω · m. It is the following. On the other hand, the specific electric resistance of copper widely used as the wire of the conductive wire used for the winding of the stator coil is about 1.7 × 10 ⁻⁸ [Ω · m]. In contrast, a wire having a high specific electric resistance is used.

  Therefore, the electrical resistance of the stator coil formed by the conductive wire of the present invention is larger than the electrical resistance of the stator coil formed by the copper conductive wire, and the lock current that flows when the outer rotor type brushless motor is locked is small. Become.

  Next, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side view of the outer rotor type brushless motor of the present embodiment in a state where a cooling fan is attached. FIG. 2 shows a cross-sectional view of the outer rotor type brushless motor of the present embodiment shown by a section AA in FIG.

  As shown in FIG. 1, the outer rotor type brushless motor 1 of this embodiment is used as a cooling fan motor for a radiator (not shown) of an automobile, for example. In such an application, a cooling fan F is attached to the rotating shaft 6 of the outer rotor type brushless motor 1 and is attached to a radiator shroud (not shown) of the automobile.

  The cooling fan F is formed of a resin, and includes a substantially bottomed cylindrical fan boss portion F1 and a plurality of fins F2 formed integrally and projecting radially outward from the outer peripheral surface of the fan boss portion F1. A hollow ring-shaped attachment portion F3 is formed at the center of the fan boss portion F1, the rotary shaft 6 is inserted inside the attachment portion F3, and the screw 12 is fastened and fixed to the screw portion 6b of the rotary shaft 6. Thus, the cooling fan F is fixed in the axial direction with respect to the rotating shaft 6.

  The rotating shaft 6 is provided with a planar chamfered portion 6a, and a flat surface portion F3m corresponding to the chamfered portion 6a is formed on the inner wall of the hollow annular mounting portion F3. The cooling fan F is fixed in the rotational direction (circumferential direction) with respect to the rotating shaft 6 by the portions F3 coming into contact with each other.

  The outer rotor type brushless motor 1 includes a housing 7, a stator 2 attached to the housing 7, and a rotor 5 disposed so as to be rotatable with respect to the stator 2. The housing 7 is formed of aluminum in a substantially disk shape, and three flanges 7 a for attachment to a radiator shroud (not shown) are integrally formed at three locations on the outer peripheral side surface of the housing 7. The flange 7a has a bolt insertion hole 7b through which a bolt (not shown) used for attachment to a radiator shroud (not shown) is inserted.

The stator 2 includes a stator core 3 formed by laminating thin steel plates that are magnetic materials, and a stator coil 4 attached to the stator core 3. The stator core 3 includes a substantially annular stator core body 3a and a plurality of teeth 3b that integrally project radially outward from the outer peripheral surface of the stator core body 3a and are formed at equal pitches in the circumferential direction. A resin insulator 9 is attached to the outer wall of the teeth 3 b of the stator core 3. In the embodiment, the number of teeth is “12”. Moreover, the thin steel plate which is a magnetic material has iron as a main component, and the density ρ0 is about 7.8 [g / cm ³ ].

  The stator coil 4 has a plurality of windings 4 a, and the winding 4 a is formed by winding a conductive wire 4 b around each tooth 3 b with concentrated windings via an insulator 9. The number of the plurality of windings 4a is “12”, which is the same as the number of teeth. The winding 4a is formed by winding the conductive material 4b "53 times" around each tooth 3b, and the so-called number of turns is "53", respectively.

  An annular convex portion 11 is integrally formed at the substantial center of the bracket 7 toward the stator 2. A bearing 10 is press-fitted and fixed inside the convex portion 11, and the rotating shaft 6 is press-fitted and fixed inside the bearing 10, so that the rotating shaft 6 is fixed to the stator 2 fixed to the bracket 7. It is pivotally supported.

  The rotor 5 includes a cylindrical rotor yoke 5a, a plurality of magnets 5b attached to the inner wall of the rotor yoke 5a, and a bottom portion 5b integrally formed at one end of the rotor yoke 5a. The shape of the rotor 5 is substantially bottomed. It is formed in a cylindrical shape. The plurality of magnets 5b are attached to the inner wall of the cylindrical rotor yoke 5a at equal pitches in the circumferential direction.

  The rotor yoke 5a of the rotor 5 is disposed outside the stator 2 so as to face the teeth 3b. A hollow annular boss 5c is formed at the center of the bottom 5b of the rotor 5. The outer wall of the rotating shaft 6 and the inner wall of the boss 5c are press-fitted and fixed so that the rotor 5 rotates. Fixed to the shaft 6. In the present embodiment, the number of the plurality of magnets is “8”.

  As described above, since the rotating shaft 6 is rotatably supported with respect to the stator 2 fixed to the bracket 7, the rotor 5 fixed to the rotating shaft 6 is attached to the stator 2 via the rotating shaft 6. It is arranged so that it can rotate freely.

  Next, the conducting wire 4b forming each winding 4a will be described with reference to FIG. FIG. 3 is a cross-sectional view of the conducting wire. The conducting wire 4b is formed of a metallic wire, and has a conductor part 4c having a circular cross section and an insulating part 4d made of a synthetic resin coated on the outer peripheral surface of the conductor part 4c.

In this embodiment, the conductor part 4c which forms the coil | winding 4a has aluminum as a main component, and the density (rho) 1 is about 2.7 [g / mm < ³ >]. The density ρ1 of the conductive portion 4c is about 2.7 [g / mm ^3] is not limited to mention, desirably 2.5 [g / mm ^3] or 3.0 [g / mm ^3] or less If it is. In the present embodiment, the composition of the insulating portion 4d covered on the outer peripheral surface of the conductor portion 4c is a polyamideimide resin.

Furthermore, the specific electric resistance of the conductor portion 4c mainly composed of aluminum of this embodiment is about 2.78 × 10 ⁻⁸ [Ω · m] at a temperature of 20 ° C. Needless to say, the specific electric resistance of the conductor portion 4c is not limited to about 2.78 × 10 ⁻⁸ [Ω · m], and desirably 2.5 × 10 ⁻⁸ [Ω · m at a temperature of 20 ° C. ] ^{May be} 3.0 × 10 ⁻⁸ [Ω · m] or less.

  In the present embodiment, the outer diameter D2 of the conductor portion 4c is about 0.9 [mm]. Since the film pressure of the insulating part 4d is about 20 [μm], the outer diameter D1 of the conductor 4b covering the conductor part 4c with the insulating part 4d is about 0.92 [mm]. Needless to say, the outer diameter D2 of the conductor portion 4c and the outer diameter D1 of the conductive wire 4b are not limited to the above numerical values, and can be changed without changing the gist of the present invention. In the present embodiment, the lead wire having a substantially circular cross section is used. However, the present invention is not limited to this, and a lead wire having a substantially square cross section may be used. Thus, by using a conducting wire having a substantially square cross section, the so-called winding space factor can be increased.

  Next, a method of winding the conductive wire 4b around each tooth 3b provided on the stator core 3 will be described with reference to FIG. As shown in FIG. 4, before the rotor 5 is disposed so as to be rotatable with respect to the stator 2, the conductive wire 4 b is wound around each tooth 3 b provided on the stator core 3 by concentrated winding.

  As described above, the resin insulator 9 is attached to the outer wall of the tooth 3 b of the stator core 3, and the conductive wire 4 b is wound around the tooth 3 b from the outside of the insulator 9 via the insulator 9.

  A slit 3c is formed between adjacent teeth 3b, 3b of each tooth 3b protruding outward in the radial direction from the outer peripheral surface of the stator core body 3a. The winding nozzle 12 is inserted into the slit 3c from the outside in the radial direction of the tooth 3b. The winding nozzle 12 turns around the one tooth 3b, and the winding 4a is fed by the conductive wire 4b fed from the winding nozzle 12 while turning. Is formed by concentrated winding.

  When the winding of the winding 4a around one tooth 3b is completed, the winding nozzle 12 winds the winding 4a around the tooth 3b adjacent to the tooth 3b after the winding of the winding 4a is completed. In this embodiment, this winding step is repeated 12 times to wind the winding 4a around the 12 teeth 3b, and the stator coil 4 is formed by these windings 4a.

Next, the effect of the outer rotor type brushless motor in the embodiment of the present invention will be described. As described above, in the embodiment of the present invention, the density ρ1 of the wire forming the conductor portion 4c of the conductive wire 4b used in the winding 4a of the stator coil 4 is about 2.7 [g / mm ³ ]. . On the other hand, the density ρ2 of copper widely used as the wire of the conductive wire used for the winding of the stator coil is about 8.9 [g / mm ³ ].

  The mass of the insulating portion 4d of the synthetic resin formed on the outer periphery of the conducting wire 4b is very small compared to the mass of the conductor portion 4c. Therefore, the mass of the conducting wire 4b of this embodiment is about 1/3 or less with respect to the mass of the wire which uses copper as a wire.

  Therefore, in the outer rotor type brushless motor 1 of this embodiment, by using the conducting wire 4b, the mass of the stator coil can be reduced by about 20% compared to the conducting wire when copper is used as the wire.

On the other hand, the density ρ0 of the steel plate mainly composed of iron used for the stator core 3 of the present embodiment is about 7.8 [g / mm ³ ], and the wire rod that forms the conductor portion 4c of the conductor 4b with respect to the density ρ0 of the steel plate. The density ρ1 is about half or less (ρ1 ≦ 0.5 × ρ0). As described above, the density ρ1 of the wire used for the conductor portion 4c is desirably 2.5 [g / mm ³ ] or more and 3.0 [g / mm ³ ] or less. The value a of the density ρ1 of the wire rod with respect to ρ0 may desirably be a relationship of 0.2 × ρ0 ≦ ρ1 ≦ 0.5 × ρ0, and more preferably the value a of the density ρ1 of the wire rod with respect to the density ρ0 of the steel plate. May have a relationship of 0.3 × ρ0 ≦ ρ1 ≦ 0.4 × ρ0.

  Thus, the density ρ0 of the steel plate mainly composed of iron used for the stator core 3 of the present embodiment is less than about half of the density ρ1 of the wire forming the conductor portion 4c of the conductor 4b with respect to the density ρ0 of the steel plate. The ratio of the mass of the stator coil 4 to the mass of 2 becomes small. As described above, the outer rotor type brushless motor 1 of the present invention is reduced in weight by using the conductive wire 4b having the density ρ1 of the wire material, and copper is used as the wire material. Compared with, its mass is greatly reduced.

Furthermore, the specific electric resistance of the wire forming the conductor portion of the conductive wire used for the winding of the stator coil is about 2.78 × 10 ⁻⁸ [Ω · m]. On the other hand, the specific electric resistance of copper widely used as the wire of the conductive wire used for the winding of the stator coil is about 1.7 × 10 ⁻⁸ [Ω · m]. In contrast, a wire having a high specific electric resistance is used.

  Therefore, the electrical resistance of the stator coil formed by the conductive wire of the present invention is larger than the electrical resistance of the stator coil formed by the copper conductive wire, and the lock current that flows when the outer rotor type brushless motor is locked is small. Become.

  Further, in the outer rotor type brushless motor 1, the teeth 3b around which the winding 4a is wound protrude radially toward the outer side in the radial direction. On the other hand, in the inner rotor type brushless motor, the teeth around which the winding is wound protrude radially toward the inside in the radial direction. Therefore, in the outer rotor type brushless motor 1, it is possible to insert a winding nozzle from the outside in the radial direction into the slit 3c formed between the adjacent teeth 3b. On the other hand, in the inner rotor type brushless motor, a winding nozzle has to be inserted from the inside in the radial direction.

  Compared with the case where the winding nozzle is inserted from the inside in the radial direction, when the winding nozzle is inserted from the outside in the radial direction, the movable range of the winding nozzle is widened, and the handling of the winding nozzle becomes much easier. Therefore, the outer rotor type brushless motor 1 is very easy to attach the stator coil 4 to the stator core 3 as compared with the inner rotor type brushless motor.

The side view of the outer rotor type brushless motor of this embodiment in the state where the cooling fan was attached is shown. The cross-sectional view of the outer rotor type brushless motor of this embodiment shown by a cross section AA in FIG. 1 is shown. It is sectional drawing of the conducting wire of this embodiment. It is a figure explaining the winding method of the conducting wire to each teeth provided in the stator core.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer rotor type brushless motor 2 Stator 3 Stator core 3a Stator core main body 3b Teeth 3c Slit 4 Stator coil 4a Winding 4b Conductor 4c Conductor part 5 Rotor 5a Rotor yoke 5b Magnet 6 Rotating shaft N Winding nozzle

Claims (2)

A stator core made of a magnetic material and having an annular stator core body, and a plurality of teeth integrally projecting radially outward from the outer peripheral surface of the stator core body radially and formed at a constant pitch in the circumferential direction, and the stator core A stator comprising a stator coil mounted on
A rotor yoke that is formed in a cylindrical shape and is disposed on the outer side of the stator so as to face the teeth; and a plurality of magnets that are attached to the inner wall of the rotor yoke at regular pitches in the circumferential direction so as to face the teeth. In an outer rotor type brushless motor provided with a rotor rotatably arranged with respect to the stator,
The stator coil has a density ρ1 of 2.5 [g / mm ³ ] or more and 3.0 [g / mm ³ ] or less, and the density of the magnetic material forming the stator core of the stator is ρ0. ρ1 has a relationship of 0.2 × ρ0 ≦ ρ1 ≦ 0.5 × ρ0, and the specific electric resistance is 2.5 × 10 ⁻⁸ [Ω · m] or more and 3.0 × 10 ⁻⁸ [Ω · m. ] A conductor having a conductor part formed of the following metal wire and an insulating part made of a synthetic resin coated on the outer peripheral surface of the conductor part is arranged so that the rotor is rotatable with respect to the stator. Previously, a winding nozzle was inserted into a slit formed between adjacent teeth from the radially outer side of the teeth protruding radially, and concentrated winding around each tooth by the winding nozzle. Have multiple windings formed Outer rotor type brushless motor according to claim Rukoto. 2. The outer rotor type brushless motor according to claim 1, wherein the conductor portion of the conducting wire forming the winding is mainly composed of aluminum, and the stator core is mainly composed of iron.

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